R help - Aug 2008 - grep, gsub and metacharacters

Hello,

   I have an expression that I want to substitute for something else.

myvector<-c("ajkhfkiuwe","Variable(kg/min)")

if I use the following code to extract "variable(kg/min)" and
substitute it for "va"

gsub(myvector[grep("var", myvector, ignore=T)], "va",
myvector)

 grep identifies the element of the vector that matches my query, but it
won't substitute the value. I have been reading the help pages for regular
expression, but still can't figure out the syntax to read parenthesis and
forward slashes, which are considered metacharacters.


As usual, thank you for your help,

Judith

Try this:
> myvector<-c("ajkhfkiuwe","Variable(kg/min)")
> gsub( "\\(kg/min\\)", "va", myvector )
Does that come close to what you want?  If not, maybe an example of what you
want the result to look like,

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111


> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Judith Flores
> Sent: Friday, August 22, 2008 10:57 AM
> To: RHelp
> Subject: [R] grep, gsub and metacharacters
>
> Hello,
>
>    I have an expression that I want to substitute for something else.
>
> myvector<-c("ajkhfkiuwe","Variable(kg/min)")
>
> if I use the following code to extract "variable(kg/min)" and
> substitute it for "va"
>
> gsub(myvector[grep("var", myvector, ignore=T)], "va",
myvector)
>
>  grep identifies the element of the vector that matches my
> query, but it won't substitute the value. I have been reading
> the help pages for regular expression, but still can't figure
> out the syntax to read parenthesis and forward slashes, which
> are considered metacharacters.
>
>
> As usual, thank you for your help,
>
> Judith
>
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